CVE-2021-34964
📋 TL;DR
This is a use-after-free vulnerability in Foxit PDF Editor's polygon annotation handling that allows remote code execution when users open malicious PDF files. Attackers can exploit this to run arbitrary code with the same privileges as the current user. All users of affected Foxit PDF Editor versions are vulnerable.
💻 Affected Systems
- Foxit PDF Editor
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control of the affected system, potentially leading to data theft, ransomware deployment, or lateral movement within the network.
Likely Case
Local privilege escalation leading to data exfiltration, malware installation, or persistence mechanisms being established on the compromised system.
If Mitigated
Limited impact due to application sandboxing or restricted user privileges, potentially resulting in application crash rather than code execution.
🎯 Exploit Status
Exploitation requires user interaction (opening malicious PDF). The vulnerability is in the Zero Day Initiative database (ZDI-21-1195).
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Foxit PDF Editor 11.1.0.52543 and later
Vendor Advisory: https://www.foxit.com/support/security-bulletins.html
Restart Required: Yes
Instructions:
1. Download latest version from Foxit website. 2. Run installer. 3. Restart system. 4. Verify version is 11.1.0.52543 or higher.
🔧 Temporary Workarounds
Disable JavaScript in Foxit PDF Editor
windowsPrevents JavaScript-based exploitation vectors
Open Foxit PDF Editor > File > Preferences > JavaScript > Uncheck 'Enable JavaScript'
Use alternative PDF viewer
allTemporarily use different PDF software until patched
🧯 If You Can't Patch
- Restrict user privileges to standard user accounts (not administrator)
- Implement application whitelisting to prevent unauthorized executables from running
🔍 How to Verify
Check if Vulnerable:
Check Foxit PDF Editor version in Help > About. If version is below 11.1.0.52543, system is vulnerable.Check Version:
In Foxit PDF Editor: Help > AboutVerify Fix Applied:
Verify version is 11.1.0.52543 or higher in Help > About. Test opening known safe PDF files to ensure functionality.📡 Detection & Monitoring
Log Indicators:
- Application crashes of Foxit PDF Editor
- Unusual process creation from Foxit processes
- Memory access violations in application logs
Network Indicators:
- Downloads of PDF files from untrusted sources
- Outbound connections from Foxit processes to suspicious IPs
SIEM Query:
Process Creation where Parent Process contains 'Foxit' AND (Command Line contains '.pdf' OR Image contains 'cmd.exe' OR Image contains 'powershell.exe')